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Fuel Distribution Problems

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Old 03-20-2017, 04:36 PM
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Fuel Distribution Problems

I have acquired a 1995 Toyota 4runner, 3VZ-E. I tested the compression on the motor before I got the vehicle and it's good. The engine would turn but not start. I inspected the fuel pump and, beside the obvious corrosion all over it, it would not activate when connecting it directly to 12V. Replaced the fuel pump but found that the circuit would not get power. After chasing a diagram I found that it may be the Fuel Pump Relay. After opening the fuel pump relay for diagnostic I saw that the coil was corroded so I replaced it. I found the the ground in the circuit was still broken so I jumped the relay to ground. Now that the fuel pump runs I try to start it and it sputters but does not run. The fuel filter was blocked but I replaced it. The previous owner says that the thing hasn't run in almost 10 years. The motor runs on starting fluid just fine and inspection of the wires and plugs have shown them to be fine. As I run the thing on ether then I have a buddy of mine pump the throttle and it seems to get better every time. Almost running on its own a couple of times.

Theories I have:
1. Jumping the Fuel Pump Relay to ground has only given the pump power in first position on the key switch but then as I turn to second position to turn the engine over then power is lost to the fuel pump, causing it to kill. Could this be a possibility? If so, where is this Air Flow Sensor that I am seeing on the diagram? It is the only thing in the circuit that I have not tested; and if it's what's causing the power interruption in the fuel circuit then I would rather just replace it than jump the relay.

2. The injectors are clogged from sitting so long. Is this a possibility? Is there an additive that I can use to clean the injectors?

3. There may be a fuel pressure problem. Maybe I purchased the wrong pump? I got the pump from Autozone and they said it was good. Advice on diagnosing fuel pressure problems?

4. There is something beyond my scope of knowledge or diagnostics. Is there any advice any of you have?
Old 03-21-2017, 12:20 AM
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Red face

It can be any of those issues you listed.

I hope your talking about the Circuit Opening Relay I have yet to see a fuel pump relay

Check the EFI relay as well

The afm is right behind the air cleaner housing.

The fuel pump will not turn on if the complete Air intake system is installed

The old fuel has been drained and replaced with new??
Old 03-21-2017, 06:09 AM
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Originally Posted by wyoming9
It can be any of those issues you listed.

I hope your talking about the Circuit Opening Relay I have yet to see a fuel pump relay

Check the EFI relay as well

The afm is right behind the air cleaner housing.

The fuel pump will not turn on if the complete Air intake system is installed

The old fuel has been drained and replaced with new??
Yes, it's the circuit opening relay on the diagram; I've had to call it the fuel pump relay to find a new one online. I've tested everything in the fuel circuit except the afm, the EFI relay is good.

Advice on testing the fuel injectors or fuel pressure? At 25 dollars a piece per injector, I don't want to just replace parts.



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